of, like or pertaining to dreams
• (a.) Of or pertaining to sleep or dreams.
Som'ni·al adjective [ Latin somnialis dream bringing, from somnium dream, from somnus sleep.] Of or pertaining to sleep or dreams. « The somnial magic superinduced on, without suspending, the active powers of the mind.» Coleridge. 
somnial Relating to sleep or dreaming.